FR2777860A1 - Simplified anti-vibration suspension for helicopter rotor - Google Patents

Abstract

The anti-vibration suspension comprises three inclined bars (8) each articulated (9,11) on the structure (1) and the on the transmission box (2) by a rigid lever (12). The lever which supports a swinging mass (13) is pivoted on the transmission box. For each inclined bar a traction bar (16) is also articulated (17,18) on the structure and the transmission box. The corresponding lever is articulated on the box by pivoting on the upper end part of the corresponding traction bar.

Description

"SIMPLIFIED ANTI-VIBRATION SUSPENSION DEVICE

WITH HIGH BEATERS FOR HELICOPTER "

  The invention relates to an anti-vibration, or anti-resonant, suspension device for the main rotor of a helicopter comprising a rotor mast rotated by a main gearbox around the axis of the mast, which is the axis of rotation of the rotor. Such a device

  of anti-vibration suspension is intended to equip a heli-

  coptère whose structure supports, in general, on a mechanical floor on top of the fuselage, a group

  powertrain, main rotor and gearbox

  main mission, acting as a reducer and located between the powertrain and the main rotor to drive the latter in rotation. Such an anti-vibration suspension device is therefore interposed between the main gearbox and the structure of the helicopter to, on the one hand, ensure transmission between the rotor and

  the structure of the static forces and moments which solicit

  tent the rotor, and, on the other hand, provide an effective damping or filtering of the dynamic components of

  forces and moments that stress the rotor, and in particular

  link the dynamic component of the force directed along the axis of the rotor (pumping) and the excitations in forces and moments

in the plane of the rotor.

  The invention relates more precisely to a

  anti-vibration suspension device of the so-called "bat-

  high teurs "and comprising a set of at least three oblique and rigid bars for supporting the gearbox on the structure of the helicopter, these slashes being distributed around the gearbox and inclined on the axis of the rotor so as to converge towards each other and substantially towards a point on the axis of the rotor, generally on the side of their upper ends and so that the point of convergence is located between the hub, in the center of the rotor, and the upper part of the gearbox, these slashes being connected by

  articulated, on the one hand, to the structure of the helicopter

  tère by their lower ends, and, on the other hand, to the gearbox by their upper ends and via rigid levers, in number equal to the slashes, each lever being oriented substantially from the

  top of the gearbox and the upper end

  lower of the corresponding oblique bar towards the base of said gearbox and / or towards the lower end of said oblique bar, each lever supporting at least one beating mass at its lower end and being hingedly connected to the gearbox by its upper end part, on which the upper end of the corresponding oblique bar is articulated, the articulations connecting each lever to said box and to the corresponding oblique bar being articulations at least pivot about axes substantially perpendicular to a plane corresponding radial passing through the axis of the rotor and

  by the longitudinal axis of the corresponding oblique bar.

  A suspension device of this type is known from FR 2 669 982, in which each slash is articulated by its lower end directly on the structure of the helicopter, and by its upper end to the upper end of one respectively. arms, equal in number to the slashes, and arranged substantially vertically around the gearbox, to the base of which these arms are connected. Each arm is articulated at the upper part of the gearbox in the rigid region of its upper end to which the corresponding rigid lever is fixed or integral by its upper end. In FR 2 669 982, each arm constitutes, with the

  lever and the corresponding beating mass, an anti

  unidirectional resonant arranged in vertical position

  around the gearbox, at the connection of the

  upper half of the corresponding slash with said box. Each arm is arranged in a radial plane defined by the axis of the rotor and the axis of the corresponding oblique bar, and its longitudinal axis extends in a direction substantially parallel to the axis of the rotor, and each arm, formed by a single elongated piece or assembly, constitutes a flexible blade in this radial plane by its lower part, the lower end of which is articulated

  on a side fitting of the base of the gearbox-

  if we. The articulations of each arm allow it to travel by deformation, perpendicular to the axis of the rotor, of its part forming a flexible blade, and the assembly of the corresponding lever and of its beating mass forms a

  beater in high position, acting by inertia and development

  pant inertia efforts that counterbalance reactions

  at the connection points to the corresponding gearbox

  due to the deformations of the flexible parts of the arms.

  In addition, and as in the anti-resonance suspension device according to FR 2 499 505, with beaters in

  low position and which FR 2 669 982 offers a perfect

  ment, a flexible suspension plate, independent of the arms and beaters and constituted by a circular crown membrane fixed under the base of the gearbox and to the structure, is deformable in bending under forces exerted perpendicular to its plane, according to the axis of the rotor, or pivoting moments exerted around its center by the gearbox, but is rigid in traction / compression under forces and moments exerted in its plane, such as the drive reaction torque

  of the rotor, this membrane integrating into the upper structure

the fuselage.

  The configuration according to FR 2 669 982 implies the use, for the connection of the lower end

  of each flexible arm at the base of the transmission box-

  sion, of a complex laminated bearing, which allows rotation about an axis perpendicular to the radial plane containing this arm and allows parasitic movement of the lower end of the flexible arm along its axis

  longitudinal, during the flexural deformation of this arm.

  This configuration also involves the use of flexible arms whose sizing and fabrication are difficult. In addition, the attachment between the rigid lever and the corresponding vertical arm can cause fretting problems.

  The problem underlying the invention is to simplify

  proud an antivibration suspension device of the type with high beaters, known from FR 2 669 982, in particular by eliminating the flexible arms in bending and their complex bearing on the base of the gearbox, so as to obtain very substantial reductions in manufacturing, installation and maintenance costs, while retaining the advantages of a high beater device according to FR 2 669 982 compared to a low beater device according to FR 2 499 505, these advantages being essentially due to the static adjustment of the suspension and vibration filtering properties, these advantages being detailed in FR 2 669 982 to which we will refer for more

clarification on this.

  Another object of the invention is to provide a simplified anti-vibration suspension device with high beaters, which remains compatible with the use of a membrane according to FR 2 669 982 or FR 2 499 505, to ensure the resumption of the reaction to drive torque and cutting forces on the base of the gearbox while providing the necessary degrees of freedom of pumping and rotation, the simplified device of the invention being simultaneously and advantageously compatible with mono or bi-directional suspensions comprising a pair of identical and parallel links articulated between the base of the gearbox and the structure, as described in FR 2 728 538 and FR 2 728 539, allowing additional savings compared to the use of a membrane. To this end, the invention provides an anti-vibration suspension device, of the type presented above, and which is characterized in that it further comprises, for each slash, a draw bar, flexible in traction, also inclined on the rotor axis in the corresponding radial plane so that the drawbars converge towards each other on the side of their upper ends, each drawbar being articulated by its upper end on the gearbox and by its end lower on the structure of the helicopter, and the corresponding lever is hingedly connected to said gearbox by being articulated, at least pivoting about an axis substantially perpendicular to said corresponding radial plane, on the upper end part of the

drawbar.

  Such a device, in which the drawbars transmit static and dynamic forces, and the oblique bars, of conventional structure, transmit dynamic forces, has the advantage of replacing each flexible arm and each support bearing of the devices of the state of the art with a drawbar much easier to size, build, assemble and maintain than

  the components to which it replaces, in a provision

  sitive whose architecture is thus simplified.

  Each drawbar may be substantially parallel to the corresponding slash, in which case it is advantageously practical for the lower ends

  the corresponding pull-up bar and forward slash

  dante are articulated on the structure by two articulations

  separate ball joints.

  But it is also possible that each drawbar and the corresponding slash are inclined towards one another, on the side of one of their ends,

  in which case, according to a simple embodiment facilitating the arti-

  culation to the structure, the lower end of the slash or respectively of the traction bar is articulated to the structure at least pivoting about a pivot axis

  passing through a ball joint of the lower end

  lower of the corresponding drawbar or respectively oblique on the structure. The lower ends of the two corresponding oblique and traction bars are thus articulated on the structure around the same articulation center, which allows not to increase the number of attachments to the upper part of the helicopter structure. . However, it remains possible that the upper or lower ends of a slash and the corresponding drawbar inclined towards one another are each articulated directly on the gearbox or the structure by one respectively of

two separate ball joints.

  Each drawbar can be radially outside the corresponding oblique bar, with respect to the axis of the rotor, in which case it is advantageous that the corresponding lever is articulated by its upper end on the upper end part of the drawbar

and / or on the gearbox.

  But it is also possible that each drawbar is radially inside the corresponding oblique bar, relative to the axis of the rotor, in which case it is advantageous that the corresponding lever is articulated by its upper end on the end upper side of the corresponding slash, substantially above the

  articulations of said lever on said box and on the end

  upper half of said drawbar.

  According to an advantageously simple, light and economical embodiment while remaining effective, at least one drawbar, but preferably each of them, comprises a composite strap comprising a winding of unidirectional rovings of reinforcing fibers agglomerated in a matrix of synthetic resin stiffened, the composite strap surrounding two ball joint supports at the ends of the drawbar for its articulation on the gearbox and on a structural support of

the structure of the helicopter.

  In a first example of a composite pull-up bar, the two ball joint supports are separated from each other by at least one filling element made of a light, cellular or foam material, also surrounded by the composite strap, this strap and the filling element or elements being enveloped, between the two end ball joints, by a composite coating comprising at least one layer of reinforcing fibers stiffened by a synthetic resin. For security reasons, in this case, it is advantageous for the transmission gearbox to have, projecting outwards and in the vicinity of the articulation of each drawbar on said gearbox, at least one crushing stop, limiting the movement of the gearbox towards the structure of the helicopter by pressing

  this crushing stop against an area of the corresponding lever

  laying in which this lever is articulated on the end

  top of the corresponding slash.

  Thus, the crushing stops make it possible to make

  pass the crushing forces in the slashes.

  Likewise, for safety against the risks of breakage of the drawbars, it is advantageous for the gearbox to have, projecting outwards and in the vicinity of the articulation of each drawbar on this box, at least one other stop or flight stop, allowing the passage of the forces in flight by the corresponding oblique bar in the event of rupture of the corresponding traction bar, by pressing against a lever zone

  corresponding to the vicinity of said articulation.

  In another embodiment, in which the composite drawbar fulfills the functions of resumption of flight forces in the event of its composite strap breaking and anti-crushing, each of the two end ball joints of the drawbar is advantageously mounted in one end of one respectively of two coaxial drums

  telescopic, at least one of which is tubular, and fitted

  chés one in the other by their other end, between two rectilinear strands of the composite strap of this drawbar, with a telescopic stroke of the two barrels which is limited, in both directions, by at least two stops, of which

  at least one is a crush stop, limiting the penetration

  cementing of the two barrels one inside the other, and of which another stop limits the exit of a barrel from the other, in the event of

failure of the composite strap.

  In a simple and practical embodiment, one of the two barrels advantageously has, in their fitted parts, at least one abutment finger projecting substantially radially from the common axis of the barrels, which is the longitudinal axis of the pull-up bar, this abutment finger being engaged in at least one oblong and axial opening formed in the other barrel and the axial ends of which constitute one a compression stop and

  and the other a cooperative extension stop

  tion with the stop finger. In addition, to improve the resistance of the device to crushing, one of the two drums advantageously also has a radial shoulder constituting a crushing stop against which the other

  shaft comes to rest after a predetermined stroke

  cementing of the two barrels into one another from a

initial position.

  Thus, the drawbar takes up the flight forces by the composite strap in normal operation and by the coaxial drums and the stop of the oblong opening in the event of rupture of the composite strap, and moreover, the two coaxial drums ensure the anti-crash function, the corresponding slash transmitting only forces

  dynamic in normal operation.

  Advantageously, at least one lever, but preferably each of them, comprises two rigid flanges parallel to each other and substantially to the axis of the rotor, spacers at least by part of the corresponding beating mass and between which axes extend pivots of the articulations of this lever on the drawbar and on the oblique bar, pivot axes being mounted on the flanges by double bearings which can be laminated and conical, or preferably cylindrical, because the pivot connections between the lever and the gearbox, on the one hand, and the lever and the slash,

  on the other hand, are solicited only by dynamic efforts

ques.

  In this case, at least one oblique bar, but preferably each of them, is articulated on the two flanges of the corresponding lever by a combined articulation with ball joint and double cylindrical or conical bearing, the ball joint at the upper end of this oblique bar being crossed by a pivot pin mounted on the flanges

by this double landing.

  In the two examples of the drawbar,

  site presented above, it is possible that the upper end of the drawbar is articulated in a yoke of the gearbox by a ball joint crossed by an axis retained on this yoke, and the corresponding rigid lever is pivotally articulated around this axis on the same yoke. In this case, and when the rigid lever comprises two parallel flanges, it is advantageous that the pivot axis of the lever on said yoke and on the drawbar is mounted on the two flanges of the lever by a

  double cylindrical or conical bearing.

  When the composite drawbar comprises two telescopic drums, it is advantageous that the lower end of the corresponding oblique bar is articulated at least pivotally on that of the two telescopic drums of the drawbar which is articulated by the ball of the lower end of this drawbar on the

structure of the helicopter.

  In this case, it is possible that the rigid lever

  corresponding either oriented substantially along the longitu-

  dinal of the corresponding drawbar and supports the corresponding swinging mass on the side of the lower ends of the drawbar and the corresponding oblique bar, with respect to the articulation of this lever on the drawbar, about an axis pivot offset, substantially along the longitudinal axis of this drawbar, relative to the ball joint of the drawbar on the gearbox, and the articulation

  of the corresponding slash on this lever being

  Saxon relative to the longitudinal axis of the lever.

  We can thus replace each slash of a conventional suspension device by a set

  articulated comprising a slash, a drawing bar

  tion, a lever and a swinging mass, so as to transform

  sea the conventional suspension device in one arrangement

tif improved according to the invention.

  To avoid the introduction of parasitic couples in

  bars, it is therefore advantageous for art centers

  culation of the lower ends of the drawbar on the structure and the corresponding slash on the drawbar and the center of articulation of the corresponding slash on the corresponding rigid lever

  are aligned in a first direction, and that the inter-

  section of this first direction with a plane passing through the center of gravity of the corresponding beating mass and transverse to this rigid lever is aligned with the centers of articulation of the upper end of this drawbar on the gearbox and this lever on

  this drawbar, static.

  In general, the drawbars are not limited, in their implementation, to the aforementioned composite structures, but at least one of them and preferably each of them, can comprise at least one elastically deformable portion under a tensile load applied to the ends of the bar, such as a ring

  and / or an axial portion of progressively evolving section

  ve, giving said bar flexibility in traction.

  Other advantages and characteristics of the invention

  tion will follow from the description given below, at

  non-limiting title, of embodiments described with reference to the accompanying drawings in which: - Figure 1 is a schematic half-view in side elevation of a first embodiment of the suspension device according to the invention, - Figure 2 is a half view similar to the figure

  1 of a second embodiment of the suspension device

  sion, - Figure 3 is a side elevational view, partially broken away, of part of an example of a suspension device according to the embodiment of Figure 1, - Figure 4 is a sectional view along IV -IV of Figure 3, - Figure 5 is a view similar to Figure 3 of another example of a device according to a variant of the embodiment of Figure 1, - Figure 6 is a view similar to Figure 5 of another embodiment, and - Figures 7 and 8 are schematic views, in side elevation, of alternative drawbars

  usable in the suspension devices of the invention

tion.

  In Figures 1 and 2, there is shown schematically-

  in 1 the resistant structure of the fuselage of a helicopter

  tere, at a mechanical floor defined by this

  resistant structure 1 above the helicopter cabin

  tère, to support a powertrain (not shown

  tee), a main gearbox 2 and a main rotor 3, the blades 4 of which are connected to a hub 5 integral in rotation with a rotor mast 6 driven in rotation, about its longitudinal axis, which is the axis of ZZ rotation of the rotor, by its base in the gearbox 2, arranged as a reduction gear on the kinematic chain between the powertrain and the mast 6, for the rotational drive of the rotor 3. The rotor 3 and the gearbox 2 are suspended on the structure 1 by a suspension device 7 or 7 'which filters the pumping excitations (according to ZZ) and the excitations due to the forces and moments in the plane of the rotor 3. This suspension device 7 or 7' comprises , like the analogous device described in FR 2 669 982, a set

  of 4 rigid and oblique bars 8 or 8 ', which are rectili-

  genes and whose longitudinal axis XX of each extends in one respectively of 4 radial half-planes passing through the axis ZZ and distributed around this axis ZZ (at 90 from each other), so that two half-planes are oriented towards the front and towards the sides of the helicopter, and that the other two half-planes are oriented towards the rear and towards the sides, the four half-planes being thus inclined each about 45 on the longitudinal axis of the helicopter. The bars 8 or 8 'are inclined in these half-planes so

  to converge towards each other, on the side of their

  upper mite, to a focal point located

  substantially on the axis ZZ, below the hub 5.

  The lower end of each oblique bar 8 or 8 'is articulated on the structure 1 by means of a ball joint 9 crossed by an axis perpendicular to the radial half-plane containing the axis XX of the bar 8 or 8' and retaining the ball 9 between the two attachment wings of a structural fitting

10 of structure 1.

  Each slash 8 or 8 'is connected so

  articulated by its upper end to the upper part

  lower of the casing of the gearbox 2, by an articulation 11 or 11 'articulating the bar 8 or 8' at least pivotally, about an axis perpendicular to the radial half-plane containing the axis XX of the bar 8 or 8 ', on the upper part of a rigid 12 or 12' straight lever arranged

  longitudinally around the edge of the gearbox-

  sion 2 and whose longitudinal axis VV is substantially parallel to the axis ZZ in the same radial half-plane containing the axis XX of the slash 8 or 8 ', and which supports a swinging mass 13 or 13' at its lower end, while, by its upper end part, the lever 12 or 12 'is articulated by an articulation 14 or 14' between the two wings of a yoke 15 or 15 'projecting radially on the upper part of the gearbox 2 so as to be able to at least pivot about an axis perpendicular to the radial plane containing the axes XX and VV of the bar

  oblique 8 or 8 'and lever 12 or 12'.

  The essential characteristic of the antivibration or anti-resonance suspension device of the invention is that it comprises, for each slash 8 or 8 ′, a

  16 or 16 'drawbar, flexible in traction and straight-

  gene, whose longitudinal axis YY extends in the radial plane containing the longitudinal axes XX and WVV of the bar 8 or 8 'and of the corresponding lever 12 or 12'. The drawbars 16 or 16 'are also inclined on the axis ZZ so as to converge towards each other on the side of their upper ends, by which the bars 16 or 16' are each articulated directly in a clevis 15 or 15 'of the upper part of the gearbox 2 by a ball joint 18 of the articulation 14 or 14' retained between the attachment wings of this yoke 15 or 15 ', while the lower end of each drawbar 16 or 16 ′ is articulated on the structure 1 by a ball joint 17 crossed by an axis retaining it between the attachment wings of the same structural fitting 10 as that

  retaining the ball joint 9 of articulation of the lower end

  lower of the corresponding slash 8 or 8 ', on the

structure 1.

  Each monodirectional anti-resonant beater, constituted by a lever 12 or 12 ′ with its beating mass 13 or 13 ′, is thus articulated on the upper end part of the corresponding draw bar 16 or 16 ′,

  at least pivoting about an axis substantially perpendicular

  cular to the corresponding radial plane, containing the axes XX, YY and VV of the bars 8 or 8 'and 16 or 16' and of the lever 12 or 12 '. In FIG. 1, each drawbar 16 is substantially parallel to the corresponding oblique bar 8 and arranged radially outside this oblique bar 8, with respect to the axis ZZ, and the lower ends of the bars 8 and 16 are articulated directly on the same

  structural fitting 10 by separate ball joints 9 and 17.

  By the articulation 14, the corresponding lever 12 is articulated by its upper end on the upper end of the drawbar 16 and on the yoke 15 of the gearbox 2, above the articulation 11 of the lever 12 on the upper end of the slash 8. But, as shown in FIG. 2, in which the same references designate similar components,

  each drawbar 16 'can be radially inside

  of the corresponding oblique bar 8 'with respect to the axis ZZ, and the corresponding lever 12' is then articulated at 11 'by its upper end on the upper end

  back of the oblique bar 8 ', substantially above the articulation 14' by which the lever 12 'is articulated

  in the clevis 15 'of the box 2 and on the upper end

of the drawbar 16 '.

  Also in this configuration, in which the two corresponding bars 8 ′ and 16 ′ are substantially inclined towards one another on the side of their upper ends, but could be substantially parallel to one another, or even inclined towards one another. other on the side of their lower ends as in the examples described below with reference to FIGS. 5 and 6, the lower ends of the bars 8 ′ and 16 ′ are articulated by two distinct ball joints 9 and 17 on the same fitting

structural 10 of structure 1.

  In devices according to FIGS. 1 and 2, the traction bars 16 or 16 ′ transmit static and dynamic forces. Dynamic efforts are

  transmitted by slashes 8 or 8 'to the battan-

  your 13 or 13 '. The beating masses thus solicited develop, by means of their lever 12 or 12 'on the yokes 15 or 15', on which the levers 12 or 12 'are articulated, dynamic forces opposed to the dynamic reactions applied to these yokes 15 or 15 'by the dynamic stresses transmitted by the slashes 8 or 8' and coming from the rotor 3 and the gearbox

  transmission 2, so as to filter these excitations.

  For safety, in the examples of FIGS. 1 and 2, anti-crushing stops 19a and 19'a are provided,

  which project substantially radially outward

  laughing on the upper part of the gearbox 2 and each opposite the upper end part

  a corresponding 12 or 12 'lever.

  In FIG. 1, each stop 19a is below the two wings of a yoke 15, facing the upper part

  the corresponding lever 12 which extends between its articulations

  tions 14 and 11 on the upper ends of the drawbar 16 and the slash 8, and in the vicinity of these joints 14 and 11, while in FIG. 2, the stop 19'a is above the wings of 'a yoke 15' and facing a prominence, projecting radially towards the axis ZZ, on

  the upper end of the lever 12 'substantially radial-

  inside the two joints 11 'and 14' of the lever 12 'on the upper ends of the bar

  oblique 8 'and drawbar 16'.

  In both cases, the stops 19a or 19'a limit the movements of the rotor 3 and of the gearbox 2 towards the structure 1 of the helicopter, in the event of the latter being crushed, by the coming into contact of the stops 19a or 19'a against the upper part of the levers 12 or 12 'in their articulation zones on the upper ends of the oblique bars 8 or 8' through which the crushing forces pass, since the traction bars 16 and 16 '' are designed to work only

traction and not in compression.

  Other stops 19b or 19'b are also provided projecting substantially radially outwards on the upper part of the gearbox 2. In FIG. 1, each stop 19b is above the corresponding stop 19a and in look of a prominence, projecting radially towards the axis ZZ, on the upper end of the lever 12, substantially radially inside the articulation 14 of the lever 12 on the upper end of the drawbar 16. In Figure 2, each stop 19'b

  is below the stop 19'a and the clevis 15 'corres-

  laying and opposite the part of the lever 12 'which extends under the articulation 14' of the lever 12 'on the yoke' and on the upper end of the drawbar

16 '.

  In the event of the bars 16 and 16 'breaking, these stops 19b and 19b come into contact with zones of the levers

  12 and 12 'which are close to the joints 14 and 14'.

  These stops 19b and 19'b thus constitute breaking stops of the drawbars 16 and 16 ', and allow the passage of forces in flight by the oblique bars 8 and

  8 'in the event of the bars 16 and 16' breaking.

  For each 12 or 12 'lever, the anti-stop

  crushing 19a or 19'a and the corresponding flight stop 19b or 19'b are offset from one another substantially in the direction of the axis ZZ of the rotor and on either side of the articulation 14 or 14 'of the lever 12 or 12' on the yoke

  or 15 'corresponding to the gearbox 2.

  The example of FIGS. 3 and 4, which corresponds to the configuration of FIG. 1, associates a metal oblique bar 8, for the transmission of dynamic forces, with a first example of a traction bar 16 essentially made of composite materials, for the transmission of flight forces. This drawbar 16 comprises two upper end ball joints 18 and lower end 17, which are each crimped in a corresponding support, consisting of a shoulder bush 20, at each end of an elongated block 21 of a synthetic material of low density, in

  foam or cell, constituting a filling element.

  The filling element 21 and the two sockets 20, containing the ball joints 17 and 18, are surrounded by a composite strap 22 constituted by a winding of unidirectional rovings of R-type glass fibers agglomerated in a matrix constituted by a synthetic resin stiffened impregnation, with a fiber content in the winding of about 25% for example. The use of ribbons made of E or S type glass reinforcing fibers is also possible. Between the two ball joints 17 and 18, the assembly consisting of the filling element 21 and the two straight, parallel and opposite strands 22a of the strap 22 which surrounds it is stabilized by a composite coating 23 comprising two superposed plies of a fabric of glass fibers which are crossed for example at about +30, that is to say such that the orientations of the warp threads of the two plies of fabric are inclined by about 30 on one side for a ply and about 30 on the other side for the other ply relative to the longitudinal axis YY of the drawbar 16, to which this composite structure gives good flexibility in traction, these two plies of fabric being agglomerated together and to the underlying structure of the element 21 and of the strap 22 by a rigidified impregnation synthetic resin, which is preferably the same resin as that of the strap 22 or a compatible resin

with her.

  This composite pull-up bar 16 is placed,

  substantially parallel to the corresponding slash 8

  dante, between the yoke 15 of the gearbox 2 and the

  structural fitting 10 on which the bar 16 is articulated

  linked by its lower ball joint 17 crossed by a retaining pin 24 between the two wings of this fitting 10, between which is also fixed the pin 25 retaining the ball joint 9 at the lower end of the bar 8, the two axes 24 and 25 being substantially perpendicular to the radial plane containing the axes XX and YY of the bars 8 and 16. The ball joint 18 of the upper end of the bar 16 is crossed by an axis 26 for retaining this ball joint 18 on the two wings of the yoke 15, this axis 26 constituting simultaneously in the articulation 14 (see FIG. 1) the pivot axis of the rigid lever 12 corresponding on these same

clevis wings 15.

  In this example, as in those of FIGS. 5 and 6 described below, the lever 12 associated with the bars 8 and 16 consists of two rigid flanges 29 substantially parallel to each other and to the radial plane containing the longitudinal axes XX, YY and VV of the bars 8 and 16 and of the lever 12, these two flanges 29 being integral with one another by spacers, and in particular, on the side of their end carrying the beating mass 13, by the central part of this mass 13 which is fixed to the corresponding ends of the two flanges 29 by two bolts 30. On either side of the joints 11 and 14 of the bars 8 and

  16 on the lever 12, the flanges 29 are also solida-

  rised by spacers such as 31, arranged between the flanges 29 and fixed to the latter by bolts 32 passing through them. Between the flanges 29 also extend the axis 26 of the articulation 14 of the lever 12 and the drawbar 16 on the wings of the yoke 15 of the box 2 as well as an axis 27 of the combined articulation 11 with ball joint 28 and double bearing 33 of the oblique bar 8 on the two flanges 29. The axes 26 and 27 are parallel to each other and

  perpendicular to the radial plane containing the longitu-

  dinals XX, YY and VV of the bars 8 and 16 and of the lever 12, and these axes 26 and 27 are pivot axes each mounted on the flanges 29 by a double laminated and conical bearing 34 or 33. These double bearings 33 and 34 have a well-known structure and each of them comprises two laminated bearings

  conical, each comprising a frustoconical elasto- ring

  mother 36 vulcanized around a frustoconical bearing of a

  ring 37 central metal surrounding a cylindrical part

  as the axis 26 or 27, the elastomer ring 36 also being vulcanized inside a frustoconical bearing of an outer metal ring 38 shouldered retained in a corresponding bore of a flange 29, and the two bearings tapered laminates of the double bearing 34 are mounted in the

  flanges 29 inside the two clevis wings 15

  seized by the bolted axis 26 with interposition of shouldered cylindrical rings 39 between which are mounted the internal rings 37 and the ball joint 18 of the upper end of the drawbar 16. The two tapered laminated bearings of the double bearing 33 ensure the same manner the pivoting mounting of the flanges 29 around the ends of the axis 27, which is bolted to the flanges 29 and which passes through the ball joint 28 at the upper end of the corresponding oblique bar 8, this ball joint 28 being disposed

  between the two internal rings 37 of the double bearing 33.

  However, like the pivoting connections around the axis 26, between the flanges 29 of the lever 12 and the yoke wings 15, and around the axis 27, between the oblique bar 8 and the flanges 29 of the lever 12, are not stressed that by dynamic forces, the double tapered laminated bearings 33 and 34 can be replaced, as a variant, by double smooth and cylindrical bearings, with rings preferably having an anti-friction coating, for example in PFTE fabric, which decreases still the costs compared to similar devices of the prior art. In FIG. 3 as in FIG. 1, the lever 12 can come into abutment by the part of its flanges 29 which extends between the articulations 11 and 14 against an anti-crushing abutment such as 19a in FIG. 1, to protect the drawbar 16 from compression, since

  this bar 16 is designed to work only in traction.

  In the event of rupture of the strap 22 of the drawbar 16, the flight forces pass through a stop such as 19b

  in FIG. 1, the stops 19a and 19b not being shown

  tees in Figure 3 so as not to overload the drawing.

  Figure 5 shows a second sensitive example -

  ment according to the configuration of FIG. 1, and which differs from the first example of FIGS. 3 and 4 by three essential differences, relating to the structure of the composite traction bar 16 ", to the fact that this bar 16"

  and the corresponding forward slash 8 "are no longer sensitive-

  ment parallel but inclined towards each other on the side of their lower ends, and finally at the joint of the lower end of the slash 8 "no longer directly on a structural support such as 10 in FIGS. 1 and 2, but on the lower end part of the drawbar 16 ", which remains articulated by its ball joint 17 at the lower end on a structural fitting

of structure 1.

  Regarding the structure of the drawbar 16 ", this bar includes a composite strap 22, identical to that of the previous example, and which surrounds the ball joint supports such as 17 and 18 at the lower and upper ends of the bar 16" . Each of these two ball joints is

  mounted in a lower end yoke 41 or higher

  corresponding lower 42 each having a groove

  outer 43 in which the composite strap is housed

  site 22 previously formed and stiffened, for example by polymerization, if the agglomeration resin of

  rovings of the reinforcing fibers is a thermoset resin

  cissable, for example of epoxy type. Each of the two end yokes 41, 42 is at one end of one respectively of two coaxial tubular drums 44 and 45 fitted one inside the other by their other end, and

  telescopic on a limited stroke in both directions.

  More specifically, the yoke 41 of the ball joint 17 of the lower end is shaped at the lower end of a barrel

  outer tubular 44 in which is fitted coaxially

  ment, along the axis YY, the lower end and most of the length of an inner tubular barrel 45, the upper end of which is shaped as a yoke 43 receiving the ball joint 18 from the upper end of this bar 16 "pull. The parts fitted one inside the other of the two drums 44 and 45 have two guide zones at the

  sliding, constituted by anti-friction coatings-

  ment 46 and 47 produced by layers of a PTFE fabric wound and fixed around the lower and upper ends of the part of the internal barrel 45 which is engaged in the external barrel 44. In the parts of the barrels fitted one in the 'other, and near the upper end of the inner barrel 45, the outer barrel 44 is secured to a diametral abutment finger 48 which passes through two oblong slots 49 formed axially in diametrically opposite parts of the inner barrel 45. In the initial and normal service position of the drawbar 16 ", the two barrels 44 and 45 are fitted one inside the other so that the finger 48 of the outer barrel 44 is not in contact

  with no end of the lights 49 of the inner barrel 45.

  In the event of a rupture of the composite strap 22, the telescopic sliding of the two barrels 44 and 45 takes place in the direction of extension, the inner barrel 45 tending to leave the outer barrel 44, until the finger 48 arrives in abutment against the lower end 49a of the oblong slots 49. This end 49a of the slots 49 thus constitutes a stop for extension, or for resumption of flight forces by the bar

  16 "in the event of its strap 22 breaking, while the end

  upper part 49b of the lights 49 constitutes a compression and crushing stop, limiting the sinking of the two drums 44 and 45 into one another and protecting the drawbar 16 "against compression. In the event of breakage of the stop finger 48 bearing against the upper end 49b of the oblong slots 49, the drawbar 16 "is

  protected against crushing by a second anti-stop

  crushing or anti-crash, constituted by a shoulder 50 projecting radially outward on the upper end portion of the inner shaft 45, and against which comes

  stop the upper end of the outer barrel 44.

  Thus, the functions of anti-crushing and resumption of forces in flight, in the event of rupture of the composite strap 22, are integrated in the drawbar 16 "of FIG. 5. In this example, the beating mass 13 is supported by a lever 12 comprising two flanges 29 as in the example of FIGS. 3 and 4, and which are articulated, on the one hand, at the upper end of the oblique bar 8 ", by a complex articulation 11 with ball joint 28 and double bearing, cylindrical or conical and laminated, around an axis 27, and on the other hand, on the upper end of the drawbar 16 "and on the clevis wings 15 of the box 2 by a double bearing cylindrical or conical and laminated surrounding a pivot axis 26 passing through the ball joint 18 of the upper end of the bar 16 ", in the same way as

shown in figure 4.

  As mentioned above, the lower end of

* the 8 "slash, sized to transmit only-

  ment of the dynamic forces in normal operation, is articulated on the lower end part of the outer barrel 44, by a pivot articulation about an axis 51 perpendicular to the radial plane containing the longitudinal axes XX, YY and VV of the 8 "bars and 16 "and of the lever 12, this axis 51 being centered on the longitudinal axis XX of the bar 8", between the axes 27 and 24 ensuring the retention of the ball joint 28 respectively of the upper end of

  the 8 "bar on the lever 12 and the ball joint 17 of the end

  lower part of the bar 16 "between two attachment wings of a structural fitting such as 10 (FIGS. 1 and 2). For this reason, the lower part of the oblique bar 8" is shaped as a yoke or a U, of which the two branches extend on either side of the lower part of the outer barrel 44 and are linked to this barrel 44 by a pivot connection around the axis 51 with possibly a double cylindrical or conical bearing such as 33 on FIG. 4. The alignment of the axes 27, 51 and 24 in the same plane passing through the longitudinal axis XX of the bar 8 "makes it possible not to introduce parasitic moments into the traction bar 16". As a variant, the lower end of the bar 8 "can be articulated by a pivot link around the axis 24 passing through the ball joint 17 articulating the lower end

of the 16 "bar on the structure 1.

  According to another variant, approaching FIG. 2, the bar 8 ", although inclined towards the bar 16" on the side of its lower end, is directly articulated on a structural support of the fuselage by a ball joint at its

lower end.

  The example of FIG. 6 is a variant of that of FIG. 5, and also comprises a drawbar 16 "with two telescopic barrels (44,45) supporting the ball joints 17, 18 of articulation at their ends and integrating a anti-crushing stop 50, as described above with reference to FIG. 5. Likewise, the example of FIG. 6 comprises a slash 8 "inclined towards the draw bar 16" on the side of its lower end by which the oblique bar 8 "is pivotally articulated about the axis 51 on the lower end portion of the bar 16", while the upper end of the bar 8 "is articulated by a complex articulation 11 with ball joint and with a double cylindrical or conical bearing, around an axis 27, between the two flanges 29 "of a lever 12" supporting

a 13 "swinging mass.

  We therefore limit ourselves to describing below the main differences of the example of FIG. 6 compared to that

in Figure 5.

  The lever 12 "is oriented substantially along the longitudinal axis YY of the bar 16" (axis common to the telescopic barrels 44 and 45 of this bar 16 "), so that this bar 16" and the bar 8 "extend substantially between the two flanges 29 "of the lever 12", which supports the swinging mass 13 "subdivided into two halves 13" a and 13 "b each bolted to the flanges 29", on either side of the two rectilinear strands 22a of the composite strap 22 of the 16 "bar, with a clearance (transverse to the longitudinal axes XX and YY of the 8" and 16 "bars) which allows the relative angular deflections of the half weights 13" a and 13 "b and the flanges 29" lever 12 "from the two bars 8" and 16 ". The swinging mass 13 "is supported on the side of the lower ends of the bars 8" and 16 ", with respect to the articulation of the lever 12" on the bar 16 ", which is no longer a pivoting articulation around the axis 26 retaining the ball joint 18 of the upper end of the bar 16 "on the yoke wings 15, as in FIG. 5, but which is a pivot joint on the upper end part of the barrel 45, upper and inner, of the drawbar 16 ", around a pivot axis 52 parallel to the pivot axis 51 and offset substantially along the longitudinal axis YY of the bar 16", from the axis 26 towards the axis 24 to

  the other end of the 16 "bar, and simultaneously light-

  eccentrically relative to the longitudinal axis YY of the bar 16 ", on the side of this axis facing two legs 29" has flanges 29 "forming a yoke inside which the ball 28 of the upper end of the bar 8 "is retained by the axis 27, thus offset from the longitudinal axis VV of the lever 12". Furthermore, as in the figure, the articulation axes 24, 51 and 27 are centered on the longitudinal axis XX of the bar 8 ", so that the centers of the joints of the bar 8" on the lever 12 "and on the bar 16" and of the bar 16 "on the structure are aligned in the same direction given by l longitudinal axis XX of the bar 8 ". In addition, the axis 52 of the pivot joint of the lever 12" on the bar 16 "is positioned and the

  mass 13 "is arranged so that point I, at the intersection

  tion of the longitudinal axis XX of the bar 8 "with the plane aa perpendicular to the longitudinal axis of the lever 12" and passing through the center of gravity of this mass 13 ", is a point aligned with the centers of the joints at the levels axes 52 and 26, on a second direction inclined to

  the longitudinal axis XX of the bar 8 ", in the static position.

  This particular geometric arrangement avoids loading the articulation of the axis 26 by moments likely

to introduce parasitic efforts.

  The articulated assembly of FIG. 6 can be

  substituted for a similar assembly of a suspension device

  antiresonance resistor of the state of the art, thanks to the fact that this assembly is articulated by ball joints 17 and 18 at the lower and upper ends of the drawbar 16 "on the available fasteners, on the one hand, on the structure from the helicopter, on the other hand, on the gearbox 2, since the corresponding oblique bar 8 "is articulated between the lever 12" and the drawbar 16 ", and this lever 12" is also articulated , at its end opposite the swinging mass 13 ", on the drawbar 16". In the devices of FIGS. 1 to 6, the metal or composite drawbars 16, 16 'or 16 "are

  straight with essentially straight edges.

  However, as shown in FIGS. 7 and 8, other alternative embodiments are possible for

  provide the required traction flexibility.

  In particular, the pull-up bar 55 of FIG. 7 can also comprise a circular or oval ring 56, elastically deformable radially, and of which are

  integral with two traction rods 57, radial and diametric

  trally opposite, rigid or flexible in traction, and fitted at their free end with ball joints 58 of articulation similar to ball joints 17 and 18 of the preceding examples, so that by traction on the connecting rods 57, the ring 56 deforms and gives the bar 55 the flexibility required in traction. As a variant, the pull-up bar 59 of FIG. 8 is a bar of rectilinear axis whose edges 60 are wavy between its two ends provided with ball joints 61 of articulation, so that the bar 59 has successive axial portions 62 of gradually evolving and repeated section, giving the bar 59 its flexibility in

  tensile by elastic axial deformation.

  In the various examples described above, it can be seen that the support lever for the beating mass can be oriented substantially in any direction within the angle defined between the vertical direction or parallel to the axis ZZ and the YY axis of the drawbar in the radial plane passing through the longitudinal axes of the two oblique and corresponding drawbars. In addition, the center of the articulation of the lower end of the corresponding oblique bar is not subjected to any constraint as regards its position in the corresponding radial plane, subject to complications of

  structure that can result to articulate suitable-

  ment the slash either independently and directly on the structure, or around the same center of articulation as

  the lower end of the drawbar corresponds to

  dante on the structure, or again on the end part

  lower part of the corresponding pull-up bar, using articulation yokes whose shapes can be complex.

Claims (22)

  1. Anti-vibration suspension device for the main rotor (3) of a helicopter comprising a rotor mast (6) rotated by a main gearbox (2) around the axis (ZZ) of the mast (6) which is the axis of rotation of the rotor (3), the suspension device (7, 7 ') comprising at least three oblique and rigid bars (8, 8', 8 ") for supporting the gearbox (2) on the structure (1) of the helicopter, the slashes (8, 8 ', 8 ") being distributed around the gearbox (2) and inclined on the axis (ZZ) of the rotor so as to converge on the side of their upper ends towards each other and substantially towards a point on the axis (ZZ) of the rotor, the oblique bars (8, 8 ′, 8 ") being connected in an articulated manner, on the one hand, to the structure ( 1) from the helicopter by their lower ends, and, secondly, to the gearbox (2) by their upper ends, and by means of rigid levers es (12, 12 ', 12 "), equal in number to the slashes (8, 8', 8"), each lever (12, 12 ', 12 ") being oriented substantially from the top of the gearbox (2 ) and from the upper end of the corresponding slash (8, 8 ', 8 ") to the base of said box (2) and / or the lower end of said slash (8, 8', 8") , each lever (12, 12 ', 12 ") supporting at least one beating mass (13, 13', 13") at its lower end and being hingedly connected to said box (2) by its upper end part , on which the upper end of the corresponding oblique bar (8, 8 ', 8 ") is articulated, the articulations connecting each lever (12, 12', 12") to said box (2) and to the   corresponding oblique bar (8, 8 ', 8 ") being articulated   at least pivot around axes (26, 27, 52) sensitive-   ment perpendicular to a corresponding radial plane passing through the axis (ZZ) of the rotor and through the longitudinal axis (x, x) of the corresponding slash (8, 8 ', 8 "), characterized in that it comprises moreover, for each oblique bar (8, 8 ', 8 "), a traction bar (16, 16', 16"), flexible in traction, also inclined on the axis (ZZ) of the rotor in the radial plane corresponding so that the drawbars (16, 16 ', 16 ") converge towards each other on the side of their upper ends, each drawbar (16, 16', 16") being articulated by its upper end on the gearbox (2) and by   its lower end on the structure (1) of the helicopter   tere, and the corresponding lever (12,12 ', 12 ") is hingedly connected to said box (2) being hinged, to   less pivoting, about an axis substantially perpendicular to   the said corresponding radial plane on the upper end part of the drawbar (16, 16 ', 16 "). 2. Suspension device according to claim 1, characterized in that each drawbar (16) is   substantially parallel to the corresponding slash (8)   you. 3. Suspension device according to claim 1, characterized in that each drawbar (16 ', 16 ") and the corresponding oblique bar (8', 8") are inclined   towards each other on the side of one of their ends.   4. Suspension device according to any one   claims 1 to 3, characterized in that each bar   tension (16, 16 ") is radially outside the corresponding slash (8, 8") relative to the axis (ZZ) of the rotor, and the corresponding lever (12, 12 ") is   articulated by its upper end on the end part   upper part of the drawbar (16, 16 ") and on the transmission box (2).   5. Suspension device according to any one   claims 1 to 3, characterized in that each bar   tension (16 ') is radially inside the corresponding oblique bar (8') relative to the axis (ZZ) of the rotor, and the corresponding lever (12 ') is articulated by its upper end on the upper end of the corresponding oblique bar (8 '), substantially above the articulations of said lever (12') on said box (2) and on   the upper end of said draw bar (16 ').   6. Suspension device according to any one   claims 1 to 5, characterized in that at least one   drawbar (16, 16 ") includes composite strap   (22), comprising a winding of rovings unidirection-   reinforcement fibers agglomerated in a stiffened synthetic resin matrix, the composite strap (22)   surrounding two articulated ball joint supports (20; 41, 42)   tion (17, 18) at the ends of the drawbar (16, 16 ") for its articulation on the gearbox (2) and on a structural support (10) of the structure (1) of the helicopter. 7. Suspension device according to claim 6, characterized in that the two supports (20) with ball joint (17, 18) are separated from each other by at least one filling element (21) made of a light material , cellular or foam, also surrounded by the composite strap (22), said strap (22) and said filling element (21) being wrapped, between the two end ball joints (17, 18), by a composite coating ( 23) comprising at least one layer of reinforcing fibers stiffened by a synthetic resin.   8. Suspension device according to claim 6, characterized in that each of the two ball joints (17, 18) end of at least one drawbar (16 ") is mounted in one end (41, 42) of the '' respectively one of two telescopic coaxial drums (44, 45) at least one of which is tubular (44), and fitted one inside the other by their other end, between two rectilinear strands (22a) of the composite strap (22) of the drawbar (16 "), with a telescopic stroke of the two barrels (44, 45) which is limited in both directions by at least two stops (49a, 49b, 50) of which at least one is a crushing stop (49b, 50), limiting the insertion of the two barrels (44, 45) into each other, and of which another stop (49a) limits the outlet of a barrel (45) outside the other (44), in case of rupture of the composite strap (22).   9. Suspension device according to claim 8, characterized in that one (44) of the two barrels (44, 45) has, in their fitted parts, at least one abutment finger (48) projecting substantially radially from to the common axis of the barrels (44, 45) which is the longitudinal axis (yy) of the drawbar (16 "), the stop finger (48) being engaged in at least one oblong opening (49) and axial formed in the other barrel (45), and the ends of which   axial (49a, 49b) constitute one of a compression stop   Zion and crush (49b) and the other an extension stop   (49a) by cooperation with the stop finger (48).   10. Suspension device according to one of   claims 8 and 9, characterized in that one (45) of   two barrels (44, 45) has a radial shoulder (50) constituting a crushing stop against which the other barrel (44) comes to bear, after a predetermined stroke of driving in of the two barrels (44, 45) one in the other at from an initial position.   11. Suspension device according to any one   claims 1 to 10, characterized in that at least one   lever (12, 12 ', 12 ") comprises two rigid flanges (29, 29") parallel to each other and substantially to the axis (ZZ) of the rotor, spacers at least by part of the beating mass (13, 13' , 13 "), and between which pivot axes (26, 52, 27) of the articulations of said lever (12, 12 ', 12") on the drawbar (16, 16', 16 ") and on the slash (8, 8 ', 8 "), the pivot pins being mounted on the flanges (29, 29") by double bearings   (33, 34) cylindrical or laminated and conical.   12. Suspension device according to claim 11, characterized in that at least one slash (8) is   articulated on the two flanges (29) of the lever (12) corresponding   laying by a joint (11) combined with ball joint (28) and double bearing (33) cylindrical or conical, the ball joint (28) at the upper end of said oblique bar (8) being crossed by a pivot axis (27 ) mounted on said   flanges (29) by said double bearing (33).   13. Suspension device according to any one   claims 1 to 12, characterized in that the end   upper of at least one drawbar (16) is articulated in a yoke (15) of said box (2) by a ball joint (18) crossed by an axis (26) retained on said yoke (15) and the rigid lever (12) corresponding is pivotally hinged about said axis (26) on the same clevis (15).   14. Suspension device according to claim   13 as attached to one of claims 11 and 12,   characterized in that the pivot axis (26) of the lever (12) on said clevis (15) and on the drawbar (16) is mounted on the two flanges (29) of said lever (12) by a double conical or cylindrical bearing (34).   15. Suspension device according to any one   of claims 1 to 14, characterized in that the ends   lower half of at least one slash (8, 8 ') and   the corresponding pull-up bar (16, 16 ') are articulated   linked to the structure (1) by two ball joints distinct (9, 17).   16. Suspension device according to any one   of claims 1 to 14, characterized in that the end   at least one slash (8 ") or lower   ment de traction (16 ") is articulated to the structure (1) at least pivoting about a pivot axis (24) passing through a ball joint (17) of articulation of the lower end of the traction bar (16 ") or respectively oblique (8")   corresponding on the structure (1).   17. Suspension device according to claim 8, characterized in that the lower end of at least one oblique bar (8 ") is articulated at least pivotally (51) on that (44) of the two telescopic drums (44, 45) of the corresponding drawbar (16 ") which is articulated by the ball joint (17) of the lower end of said bar   (16 ") on the structure (1).   18. Suspension device according to claim 17, characterized in that at least one rigid lever (12 ") is oriented substantially along the longitudinal axis (yy) of the corresponding pull-up bar (16") and supports the beating mass (13 ") corresponding to the side of the lower ends of the corresponding drawbar (16") and slash (8 "), with respect to the articulation of said lever (12") on said drawbar (16 " ), around a pivot axis (52) offset, substantially along the longitudinal axis (yy) of said draw bar (16 "), relative to the ball joint (18) of articulation of said pull bar ( 16 ") on said box (2), and the articulation (11) of the corresponding oblique bar (8") on said lever (12 ") being offset from the longitudinal axis (vv) of said lever (12 ").   19. Suspension device according to claim 18, characterized in that the articulation centers (24, 51) of the lower ends of at least one drawbar (16 ") on the structure (1) and of the slash (8 ") corresponding on said draw bar (16") and the   center of articulation (27) of the oblique bar (8 ") corresponding   laying on the corresponding rigid lever (12 ") are aligned on a first direction (xx), and the intersection of this first direction (xx) with a passing plane (a, a)   by the center of gravity of the beating mass (13 ") corresponding   laying and transverse to said rigid lever (12 ") being   aligned with the articulation centers (26, 52) of the end   upper half of said draw bar (16 ") on said box (2) and of said lever (12") on said pull bar (16 "), static.   20. Suspension device according to one of   claims 1 to 17, characterized in that said box of   transmission (2) has, projecting outwards and in the vicinity of the articulation (14, 14 ') of each drawbar (16, 16') on said box (2), at least one crushing stop (19a, 19'a), limiting the displacement of said box (2) towards the structure (1) by pressing against a zone of said corresponding lever (12, 12 ') in which said lever (12, 12') is articulated on the upper end of   the corresponding slash (8, 8 ').   21. Suspension device according to any one   of claims 1 to 17 and 20, characterized in that   said transmission box (2) has, projecting outwards and in the vicinity of the articulation (14, 14 ') of each drawbar (16, 16') on said box (2), at least one stop (19b, 19'b) of flight, allowing passage   efforts in flight by the oblique bar (8, 8 ') corresponding   dante in case of rupture of the corresponding pull-up bar (16, 16 '), by pressing against an area of the lever (12, 12') corresponding to the vicinity of said articulation (14, 14 '). 22. Suspension device according to any one   of claims 1 to 21, characterized in that one at   least of the tension bars (55, 59) comprises at least one portion (56, 62) elastically deformable under a tensile load applied to the ends (58, 61) of the bar (55, 59), such as a ring ( 56) and / or an axial portion of progressively evolving section (62), giving said   bar (55, 59) flexibility in traction.